Re: rtl8xxxu 4.4.5(from f23): I get a panic adding a new device to the driver

[Jes Sorensen <Jes.Sorensen@redhat.com>]

Greg KH <greg@kroah.com> writes:
> On Thu, Mar 17, 2016 at 09:01:25PM +0100, poma wrote:
>> On 17.03.2016 19:02, Jes Sorensen wrote:
>> > Jes Sorensen <Jes.Sorensen@redhat.com> writes:
>> >> Xose Vazquez Perez <xose.vazquez@gmail.com> writes:
>> >>> Hi,
>> >>>
>> >>> If I do:
>> >>> # echo "0bda 8176" > /sys/bus/usb/drivers/rtl8xxxu/new_id
>> >>
>> >> Hi Xose,
>> >>
>> >> Yes please don't do that. The rtl8xxxu driver relies on the .driver_info
>> >> field in struct use_device_id to carry information for the different
>> >> types of devices. If you hot add a device like above, the driver will
>> >> fail because that field now contains a NULL pointer.
>> >>
>> >> I should probably add a check for it in the probe function, but it will
>> >> simply be there to spit out a warning that it doesn't work to hot add a
>> >> device like this.
>> >>
>> >> If you build it with CONFIG_RTL8XXXU_UNTESTED the 0bda:8176 should be
>> >> included in the device list.
>> >>
>> >> Cheers,
>> >> Jes
>> > 
>> > Hi Xose,
>> > 
>> > I added the following patch to my tree to avoid this.
>> > 
>> > Cheers,
>> > Jes
>> > 
>> > commit 9202f4947aac1d60084ee79c9b5294eb42ba59dc
>> > Author: Jes Sorensen <Jes.Sorensen@redhat.com>
>> > Date:   Thu Mar 17 13:53:48 2016 -0400
>> > 
>> >     rtl8xxxu: Fix OOPS if user tries to add device via /sys
>> >     
>> >     This driver relies on driver_info in struct usb_device_id, hence
>> >     adding a device via  /sys/bus/usb/drivers/rtl8xxxu/new_id would result
>> >     in a NULL pointer dereference.
>> >     
>> >     Instead print a message and return -ENODEV
>> >     
>> >     Reported-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
>> >     Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
>> > 
>> > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
>> > b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
>> > index 8d893f4..55fc00e 100644
>> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
>> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
>> > @@ -9671,6 +9671,15 @@ static int rtl8xxxu_probe(struct
>> > usb_interface *interface,
>> >  
>> >  	udev = usb_get_dev(interface_to_usbdev(interface));
>> >  
>> > +	if (!id->driver_info) {
>> > +		dev_warn(&udev->dev,
>> > + "rtl8xxxu relies on driver_info in struct usb_device_id.\n");
>> > +		dev_warn(&udev->dev,
>> > + "Adding a device via /sys/bus/usb/drivers/rtl8xxxu/new_id is not
>> > supported!\n");
>
> We do have a flag in the USB driver structure to prevent this from
> happening, "no_dynamic_id", please just set that and then this should
> not happen.

I wasn't aware of this flag - I'll update the patch to do that.

Thanks,
Jes